Anyway, here is the another study that pretends to slow that using a cellphone for more than a decade can double the risk of some types of brain tumors.

Dr. Lennart Hardell and scientists at the University Hospital in Orebro, Sweden said their analysis of previous studies shows "a consistent pattern of increased risk for acoustic neuroma and glioma."

Acoustic neuromas are benign growths on the nerve linking the ear to the brain, while gliomas are malignant, difficult-to-treat tumors of the brain and nervous system. The researchers also found that the greatest risk of developing a tumor is on the side of the head where the phone was held.

Hardell and his team identified 18 studies of brain tumor risk among long-term cellphone users, 11 of which provided data for 10 years or longer.

When the findings were analysed collectively, the researchers found people who had used cellphones for at least a decade had a 2.4-fold greater risk of acoustic neuromas and were twice as likely to develop gliomas.

Scientists fear mobile phones could boost brain tumor risk by exposing the brain to electromagnetic energy. But early studies did not have a long enough follow-up time to fully account for long-term risk, Hardell and his team reported in journal Occupational Environmental Medicine.

Enough time has now passed since mobile phones were introduced to analyse risks of cellphone use for 10 years or longer, which they believe is a "reasonable minimum period" to estimate risk.

One study in the analysis found no increased tumor risk with cellphone use, but did show that cellphone users who developed brain tumors had larger tumors than non-cellphone users.

They found the greatest risk was for tumors in the area of the brain with the most exposure and the study periods allowed enough time for tumors to develop. But the researchers added that longer follow-up is needed, because an increased risk for other types of brain tumors cannot be ruled out.